Field of the Invention
Embodiments of the invention relate to touch surfaces, and, in particular, to electrovibration for touch surfaces.
Description of the Related Art
Touch provides humans with a wide variety of sensations that allow us to feel the world. We can enjoy the feeling of textures, as well as objects and materials. Beyond experience, tactile sensations also guide us with everyday tasks and help us to explore object properties that we normally are not able to see.
Interest in designing and investigating haptic interfaces for touch-based interactive systems has been rapidly growing in recent years. Haptics refers to the sense of touch. This interest in haptic interfaces is fueled by the popularity of touch-based interfaces, both in research and end-user communities. However, one major problem with touch interfaces is the lack of dynamic tactile feedback. A lack of haptic feedback decreases the realism of visual environments, breaks the metaphor of direct interaction, and reduces interface efficiency because the user can not rely on familiar haptic cues for accomplishing even the most basic interaction tasks.
In general, adding tactile feedback to touch interfaces has been challenging. In one conventional approach, the touch surface itself can be actuated with various electromechanical actuators, such as piezoelectric bending motors, voice coils, and solenoids. The actuation can be designed to create surface motion either in the normal or lateral directions. Such an approach has been used in the design of tactile feedback for touch interfaces on small handheld devices by mechanically vibrating the entire touch surface. With low frequency vibrations, a simple “click” sensation can be simulated. A major challenge in using mechanical actuation with mobile touch surfaces is the difficulty of creating actuators that fit into mobile devices and produce sufficient force to displace the touch surface. Creating tactile interfaces for large touch screens, such as interactive kiosks and desktop computers, allows for larger actuators. Larger actuated surfaces, however, begin to behave as a flexible membrane instead of a rigid plate. Complex mechanical deformations occur when larger plates are actuated, making it difficult to predictably control tactile sensation or even provide enough power for actuation.
An alternative approach to actuation of the touch surface is to decouple the tactile and visual displays. In the case of mobile devices, tactile feedback can be provided by vibrating the backside of the device, stimulating the holding hand. Alternatively, it is possible to embed localized tactile actuators into the body of a mobile device or into tools used in conjunction with touch interfaces. This approach, however, breaks the metaphor of direct interaction, requires external devices, and still does not solve the problem of developing tactile feedback for large surfaces.
Accordingly, there remains a need in the art for a user interface for a haptic interface that addresses the drawbacks and limitations discussed above.